Sexual health promotion and the provision of sexual and reproductive health and HIV services make an important contribution to both individual and population health. Sexually transmitted infections (STIs) are often asymptomatic. If left untreated, they can cause pelvic inflammatory disease or infertility, and may be transmitted to others. This highlights the need for early detection and treatment.
In 2017, there were 422,147 new sexually transmitted infection (STI) diagnoses made at sexual health services in England. Of these, the most commonly diagnosed STIs were chlamydia (203,116; 48% of all new STI diagnoses), genital warts (59,119; 14%) and gonorrhoea (44,676; 11%).
Between 2008 and 2017, rates of new diagnoses increased for chlamydia (an 8% increase, from 342 to 368 per 100,000 population), genital herpes (an 18% increase, from 50 to 59 per 100,000 population) and gonorrhoea (a 180% increase, from 29 to 81 per 100,000 population). Over the same time period, there was a decline in genital warts (a 29% decrease from 151 to 107 per 100,000 population). More recently, the rate of syphilis diagnoses has risen from 5.6 per 100,000 population in 2012 to 12.9 per 100,000 population in 2017.
The observed rising trends in STIs may be attributed to both more routine testing and case finding in genitourinary medicine and sexual and reproductive health services, and also to continued unsafe sexual behaviour. For example, it is likely that condomless sex associated with HIV seroadaptive behaviours is contributing to the increases in syphilis amongst men who have sex with men (MSM). Of increasing concern is the rise in gonorrhoea diagnosis, especially within a context of antimicrobial resistance for this STI.
The National Chlamydia Screening Programme provides opportunistic screening to sexually active young people aged 15 to 24 years, with the aim of increasing the detection of chlamydia and reducing the prevalence of associated health outcomes. In 2017, more than 1.3 million chlamydia tests were carried out among young people aged 15 to 24 years in England. A total of 126,828 chlamydia diagnoses were made among this age group.
Assuming one test per person, the proportion of the population aged 15 to 24 screened for chlamydia decreased from 27% in 2012 to 19% in 2017. Alongside this, the number of diagnoses per 100,000 people aged 15 to 24 years (the chlamydia detection rate) declined from 2,095 in 2012 to 1,882 in 2017. These decreases are likely to reflect a reduction in service provision. The Department of Health Public Health Outcomes Framework recommends that local areas aim to achieve a chlamydia detection rate among 15 to 24 year olds of at least 2,300 per 100,000 people.
A key strategic priority is to decrease HIV-related morbidity and mortality by reducing the proportion and number of HIV diagnoses made at a late stage of infection. People who are diagnosed late have a ten-fold risk of death compared with those diagnosed promptly. This indicator measures late HIV diagnoses as the percentage of adults (aged 15 or above) with a CD4 cell count of less than 350 cells per mm3 within 91 days of diagnosis. It indirectly informs our understanding of the proportion of HIV infections that are undiagnosed.
Between 2008 and 2015, the proportion of people in the UK diagnosed with HIV at a late stage of infection decreased from 55% to 40%, with the absolute number falling from 3,221 to 1,885. Since then, the proportion of late HIV diagnoses has increased again, reaching 43% in 2017. However, the absolute number of late diagnoses has continued to fall to 1,352 due to the total reduction in HIV diagnoses.
The overall decline is attributable to reductions in late HIV diagnoses among heterosexual men (from 67% in 2008 to 59% in 2017), heterosexual women (from 62% to 50%) and men who have sex with men (from 43% to 33%). Although the highest number of people diagnosed late is among men who have sex with men have, HIV cases which are diagnosed at a late stage of infection remain a significant concern among heterosexuals and disproportionately among black people.
About this data
This indicator uses data from Public Health England on sexual health services and diagnoses of sexually transmitted infections (STIs). The diagnosis rate of an STI is defined as the number of diagnoses among people accessing sexual health services (SHS) in England who are also residents in England, expressed as a rate per 100,000 population. SHS includes both specialist (level 3) and non-specialist (level 1 and 2).
The data represents the number of diagnoses reported and not the number of people diagnosed. Rates were calculated using ONS population estimates for 2016. Note that the data for chlamydia from 2012 onwards is not comparable to data from previous years (from 2008-2011 the data related to those aged 15-24 and from 2012-2017 the data related to those of all ages). Further to this, the diagnosis totals for the other STIs from 2012 onwards include data from specialist SHS (Level 3) and non-specialist SHS (Level 2) so are not comparable to data from previous years.
The chlamydia tests data includes those carried out on people aged 15 to 24 years inclusive. The data represents the number of tests and diagnoses reported, and not the number of unique people tested or diagnosed. A maximum of one chlamydia test per individual is counted within a six-week period, and the data presented are based on tests with confirmed positive and negative results only.
Late diagnosis of HIV in adults is defined as those aged 15 years and above who are diagnosed with a CD4 cell count <350 within 91 days of diagnosis in the UK.
For more information on these statistics, please see Public Health England's Sexual and Reproductive Health Profiles.